Drop Eclipse instructions (#53667)
Drop Eclipse instructions (#53667)

Hacking Elasticsearch with Eclipse is fairly broken. Some things work,
but we can't in good concience point contributors to Eclipse. This drops
the instrucions for Eclipse from CONTRIBUTING.md. We *do* want to fix
Eclipse. But we don't see that happening in the next few months. Once we
*have* fixed Eclipse we'll rewrite the instructions.

Relates #53664
gingerwizard/elasticsearch,robin13/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,nknize/elasticsearch